Noncorrosive alcoholic solution



under ordlnary condltlons and considerable Patented Mar. 1, 1932 UNITED STATES PATENT OFFICE WILLIAM S. OALOOTT, OF PENN GROVE, NEW JERSEY, AND HERBERT W. WALKER, OF WILMINGTON, DELAWARE, ASSIGNORS TO E. I. DU PON T DE NEMOURS & COMPANY,

.OF WILMINGTON, DELAWARE, A CORPORATION OF DELAWARE NONCORROSIVE ALCOHOLIC SOLUTION No Drawing.

This invention relates to the preparation of aqueous alcoholic solutions which are substantially inert with respect to iron. More particularly it pertains to the use of alkyl and alkylol amines as a class of compounds which act as inhibitors for iron corrosion by aqueous solutions of mono and polyhydric alcohols.

It is well known that Water solutions 0 alcohols attack metallic iron very rapidly corrosion as manifested by rust spots, deposits, and sediment takes place.

We have found that if a'small amount of an alkyl amine, such as, di-n-propylamine iso propylamine, di-butyl amine, or iso amylaminc, be added to a mono or polyhydric alcohol and the alcohol then diluted with water to any desired concentration there results a solution in which iron does not readily corrode. The presence of one of these amines prevents the iron from rusting and the metal remains bright, lustrous and free from scale and rust deposits. The alkyl amines have the general formula .to a monoor polyhydric alcohol and the alcohol then diluted with water to any desired concentration, there results a solution in which the rate of corrosion of the iron is much less than in a solution not so treated with ethanol amines. A distinct protective action on iron is observed in alcohol solutions treated with these ethanol amines after heating several hours at 8590. In place of the ethanol amines a water soluble alkylol aminesuch as methanolamine or propanol amine lnay be employed. The alkylolamines have the general formula cannon N-R; R; where R, andiR represent either hydrogen or an alkyl or hydroxy-alkyl radical.

Application filed September 11, 1928. Serial'No. 305,319.

For purposes of illustration the following,

examples are furnished.

Emample 1.If di-butylamine in an amount sufficient to make 0.1% of the final solution be added to methyl alcohol, ethyl alcohol, glycerine or glycol and water added to the alcoholic solution of the amine to produce a 40% solution of alcohol there is thereby formed a solution which effectively inhibits the corrosion of iron ordinarily taking place in these solutions.

Emample 2.If diethanol amine or a mixture of 80% tri-ethanolamine and 20% diethanol amine in an amount sufiicient to make 0.1% of the final water solution be added to ethyl alcohol, lycerine or glycol and water added to the a coholic solution of the amine to produce a 40% solution of alcohol there is thereby. formed a solution which effectively inhibits the corros'ionof iron ordinarily taking place in, these solutions.

With the high boiling amines the property I of inhibiting corrosion is retained at elevated temperatures, for example, at the boiling point'of water. Such amines can therefore be advantageously employed to prevent corrosion of automobile radiators by mono and polyhydrio alcohol anti-freeze mixtures, as-

ited except as indicated by the scope of the appended claims.

Also, itwill be understood that the amines maybe used either singly or in combination, and may be employed to inhibit corrosion by a mixture of alcohols as well as to inhibit corrosion by individual alcohols.

We claim:

1. A process for minimizing the corrosion of iron by an aqueous alcoholic solution in contact therewith, which comprises contacting said solution with iron inthe presence of a water soluble amine of the group consisting of alkyl and alkylol amines.

2. A process for minimizing the corrosion of iron by an aqueous alcoholic solution in contact therewith, which comprises contacting said solution with iron in the presence of an amine of the group consisting of di-npropylamine, iso-propylamine, di-butylamine, iso-amylamine, and the mono, di and triethanolamines.

3. A process for minimizing the corrosion of iron in the presence of an aqueous solution of an alcohol of the group consisting of methyl and ethyl alcohols, glycerine and glycol, which comprises contacting said solution with iron in the presence of a water soluble amine of the group consisting of alkyl and alkylol amines.

- 4. A process for minimizing the corrosion of iron by an aqueous alcoholic solution, which comprises contacting said solution with iron in the presence of a water soluble alkylol amine.

5. A process for inhibiting the corrosion of iron by an aqueous alcoholic solution in contact therewith, which comprises contacting said solution with iron in the presence of an ethanol amine.

6. A process for inhibiting the corrosion of iron by an aqueous alcoholic solution in contact therewith, which comprises contacting said solution with iron in the presence of tri-ethanol amine.

7. A process for inhibiting the corrosion of iron by an aqueous alcoholic solution, which comprises contacting said solution with iron in the presence of a mixture of diand triethanol amines.

8. A non-corrosive mixture comprising an alcoholand an'amine of the group consisting of di-n-pr'opylamine, iso-propylamine, di-

butylamine, iso-amylamine and the mono, di and tri-ethanol amines.

9. A non-corrosive mixture comprising an aqueous solution of an alcohol of the group consisting of methyl and ethyl alcohols, glycerine and glycol and tri-ethanol amine.

- 10. A non-corrosive mixture comprising an alcohol and a mixture of diand tri-ethanol amines.

In testimony whereof we afiix our signatures.

WILLIAM S. OALCOTT. 5o HERBERT W. WALKER. 

